From 5636ccd000df8f612d86b588b103186641ee192d Mon Sep 17 00:00:00 2001
From: algoidurovic <91566643+algoidurovic@users.noreply.github.com>
Date: Fri, 15 Oct 2021 16:33:45 -0400
Subject: [PATCH] Optimization for constant assembly (#128)

* Optimization added for repeated int constants under 2**7 w/ tests

* fixed type problem and formatted

* Expanded test and added comment for clarification
---
 pyteal/compiler/constants.py      | 13 ++++--
 pyteal/compiler/constants_test.py | 74 +++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 3 deletions(-)

diff --git a/pyteal/compiler/constants.py b/pyteal/compiler/constants.py
index 5152122a4..6d54e6607 100644
--- a/pyteal/compiler/constants.py
+++ b/pyteal/compiler/constants.py
@@ -132,7 +132,14 @@ def createConstantBlocks(ops: List[TealComponent]) -> List[TealComponent]:
     sortedInts = sorted(intFreqs, key=lambda x: intFreqs[x], reverse=True)
     sortedBytes = sorted(byteFreqs, key=lambda x: byteFreqs[x], reverse=True)
 
-    intBlock = [i for i in sortedInts if intFreqs[i] > 1]
+    # Use Op.pushint if the constant does not occur in the top 4 most frequent and is smaller than
+    # 2 ** 7 to improve performance and save block space.
+    intBlock = [
+        val
+        for i, val in enumerate(sortedInts)
+        if intFreqs[val] > 1 and (i < 4 or isinstance(val, str) or val >= 2 ** 7)
+    ]
+
     byteBlock = [
         ("0x" + b.hex()) if type(b) is bytes else cast(str, b)
         for b in sortedBytes
@@ -151,13 +158,13 @@ def createConstantBlocks(ops: List[TealComponent]) -> List[TealComponent]:
 
             if basicOp == Op.int:
                 intValue = extractIntValue(op)
-                if intFreqs[intValue] == 1:
+                if intValue not in intBlock:
                     assembled.append(
                         TealOp(op.expr, Op.pushint, intValue, "//", *op.args)
                     )
                     continue
 
-                index = sortedInts.index(intValue)
+                index = intBlock.index(intValue)
                 if index == 0:
                     assembled.append(TealOp(op.expr, Op.intc_0, "//", *op.args))
                 elif index == 1:
diff --git a/pyteal/compiler/constants_test.py b/pyteal/compiler/constants_test.py
index 8c169dac9..12d97b328 100644
--- a/pyteal/compiler/constants_test.py
+++ b/pyteal/compiler/constants_test.py
@@ -545,3 +545,77 @@ def test_createConstantBlocks_tmpl_all():
 
     actual = createConstantBlocks(ops)
     assert actual == expected
+
+
+def test_createConstantBlocks_intc():
+    """Test scenario where there are more than 4 constants in the intcblock.
+    If the 4th constant can't fit in one varuint byte (more than 2**7) it
+    should be referenced with the Op.intc 4 command.
+    """
+
+    ops = [
+        TealOp(None, Op.int, 0),
+        TealOp(None, Op.int, 0),
+        TealOp(None, Op.int, 1),
+        TealOp(None, Op.int, 1),
+        TealOp(None, Op.int, 2),
+        TealOp(None, Op.int, 2),
+        TealOp(None, Op.int, 3),
+        TealOp(None, Op.int, 3),
+        TealOp(None, Op.int, 2 ** 7),
+        TealOp(None, Op.int, 2 ** 7),
+    ]
+
+    expected = [
+        TealOp(None, Op.intcblock, 0, 1, 2, 3, 2 ** 7),
+        TealOp(None, Op.intc_0, "//", 0),
+        TealOp(None, Op.intc_0, "//", 0),
+        TealOp(None, Op.intc_1, "//", 1),
+        TealOp(None, Op.intc_1, "//", 1),
+        TealOp(None, Op.intc_2, "//", 2),
+        TealOp(None, Op.intc_2, "//", 2),
+        TealOp(None, Op.intc_3, "//", 3),
+        TealOp(None, Op.intc_3, "//", 3),
+        TealOp(None, Op.intc, 4, "//", 2 ** 7),
+        TealOp(None, Op.intc, 4, "//", 2 ** 7),
+    ]
+
+    actual = createConstantBlocks(ops)
+    assert actual == expected
+
+
+def test_createConstantBlocks_small_constant():
+    """If a constant cannot be referenced using the intc_[0..3] commands
+    and it can be stored in one varuint it byte then Op.pushint is used.
+    """
+
+    for cur in range(4, 2 ** 7):
+        ops = [
+            TealOp(None, Op.int, 0),
+            TealOp(None, Op.int, 0),
+            TealOp(None, Op.int, 1),
+            TealOp(None, Op.int, 1),
+            TealOp(None, Op.int, 2),
+            TealOp(None, Op.int, 2),
+            TealOp(None, Op.int, 3),
+            TealOp(None, Op.int, 3),
+            TealOp(None, Op.int, cur),
+            TealOp(None, Op.int, cur),
+        ]
+
+        expected = [
+            TealOp(None, Op.intcblock, 0, 1, 2, 3),
+            TealOp(None, Op.intc_0, "//", 0),
+            TealOp(None, Op.intc_0, "//", 0),
+            TealOp(None, Op.intc_1, "//", 1),
+            TealOp(None, Op.intc_1, "//", 1),
+            TealOp(None, Op.intc_2, "//", 2),
+            TealOp(None, Op.intc_2, "//", 2),
+            TealOp(None, Op.intc_3, "//", 3),
+            TealOp(None, Op.intc_3, "//", 3),
+            TealOp(None, Op.pushint, cur, "//", cur),
+            TealOp(None, Op.pushint, cur, "//", cur),
+        ]
+
+        actual = createConstantBlocks(ops)
+        assert actual == expected